refactor(dev): rewrite to support --no-fork and improve stability

[pi0]

This PR applies relatively large amounts of refactoring to the dev command:

• Extract base nuxt dev server logic to shared util
• Support --no-fork mode without spawning a new process
• Improved loading handler by eagerly loading template and providing nitro dev handler all the times

There might be some small regressions with this changes but i think overall better stability is worth to try and iterate faster. Checking locally little bit more to make sure there are not odd issues.

TODO: I am working to always initialize an internal listener + proxy. This patterns helps on HTTPs + Expose host stability for vite-node and internal calls.